Ground excavating apparatus

Abstract

To improve the excavation capacity of a ground excavator by a simple constitution.SOLUTION: A soil drilling device includes a drilling shaft (11) rotatable about an axial line (11a) extending in a vertical direction, a pair of drilling blades (1213) extending from the drilling shaft (11) to one side and the other side of a radially outer side, and a plurality of drilling blades (14) provided at intervals in the radial direction and extending downward from the drilling blades (1213), in which a lower end of the drilling blade (14) closer to the drilling shaft (11) in the radial direction is positioned lower.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ground drilling device. [Background technology]

[0002] Conventionally, a known ground drilling device includes a drilling shaft that can rotate around an axis extending in the vertical direction, a pair of drilling wings that extend radially outward from the drilling shaft, and a plurality of drilling blades that are spaced apart radially and extend downward from the drilling wings (see, for example, Patent Document 1). The ground excavation device as disclosed in Patent Document 1 is used, for example, in a deep mixing treatment method for constructing columnar improvement bodies in the ground. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-73332 Summary of the Invention [Problem to be solved by the invention]

[0004] When excavating ground using deep mixing treatment methods, excavation may be required down to the hard ground that serves as the supporting ground. However, hard ground is often difficult to penetrate due to its high strength. For this reason, it is desirable to improve the excavation capacity of ground excavation equipment. Furthermore, using an excavator that can rotate with high torque makes it easier to excavate hard ground, but this increases the size of the equipment.

[0005] In view of the above, an object of the present invention is to improve the excavation capacity of a ground excavation device with a simple configuration. [Means for solving the problem]

[0006] The ground drilling device is equipped with a drilling shaft that can rotate around an axis extending in the vertical direction, a pair of drilling wings that extend radially outward from the drilling shaft on one side and the other, and a plurality of drilling blades that are spaced apart radially and extend downward from the drilling wings, and the lower ends of the drilling blades are located lower the closer the drilling blade is to the drilling shaft in the radial direction. [Effects of the Invention]

[0007] According to the present invention, the excavation capacity of a ground excavation device can be improved with a simple configuration. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a side view of a ground excavation device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a view of the earth excavation equipment as seen from below. [Figure 3] FIG. 10 is a diagram showing the trajectory of rotation of the excavation blade due to rotation of the excavation shaft. [Figure 4] FIG. 4 is a side view of a ground excavation device according to a second embodiment of the present invention. [Figure 5A] FIG. 10 is a diagram showing the attached state of the excavation blade. [Figure 5B] FIG. 10 is a diagram showing a state in which the angle of the excavation blade is changed. [Figure 6A] 10A and 10B are diagrams showing excavation blades of other shapes; [Figure 6B] 10A and 10B are diagrams showing excavation blades of other shapes; [Figure 7A] FIG. 10 is a diagram illustrating a modified example of the second embodiment. [Figure 7B] 7B is a diagram showing a state in which the angle of the digging blade is changed from the state in FIG. 7A. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of a ground drilling device according to the present invention will be described with reference to the accompanying drawings.

[0010] [First embodiment] Fig. 1 is a side view of a ground excavation device 10 according to a first embodiment of the present invention. Fig. 2 is a view of the ground excavation device 10 as seen from below. The ground excavation device 10 is used in a deep mixing treatment method in which excavated soil is mixed with a ground improvement material such as cement milk while excavating the ground, thereby creating a columnar improved body in the ground. The ground excavation device 10 is attached to a ground improvement machine (not shown) that is installed on the ground. This ground improvement machine is equipped with a drilling rod (not shown) that is driven to rotate and can move up and down. The ground excavation device 10 is an excavation and mixing head that is detachably attached to the lower end of the drilling rod.

[0011] The ground drilling device 10 comprises a drilling shaft 11 connected to the lower end of the drilling rod, a pair of drilling wings 12, 13 provided at the lower end of the drilling shaft 11 and rotating integrally with the drilling shaft 11, and drilling blades 14 provided on the drilling wings 12, 13. Specifically, the drilling wing 12 is one of the drilling wing extending from the outer periphery of the drilling shaft 11 to one radially outer side of the drilling shaft 11. The drilling wing 13 is the other of the drilling wing extending from the outer periphery of the drilling shaft 11 to the other radially outer side of the drilling shaft 11.

[0012] Furthermore, the ground drilling device 10 is equipped with a stirring blade (not shown) that is provided on the drilling shaft 11 above the drilling blades 12, 13 and rotates integrally with the drilling shaft 11, and a co-rotation prevention blade (not shown) that is provided above the drilling blades 12, 13 and can rotate freely relative to the drilling shaft 11.

[0013] The center line of the drilling shaft 11 is an axis 11a extending in the vertical direction. The axis 11a is coaxial with the rotation center axis of the drilling rod, and when the drilling rod is driven to rotate, the drilling shaft 11 rotates integrally with the drilling rod around the axis 11a. Figure 2 is a view of the ground excavation device 10 as seen from below in the axial direction of the excavation shaft 11. Figure 2 also shows the rotation direction R (counterclockwise in Figure 2) of the excavation shaft 11 when the ground excavation device 10 excavates the ground.

[0014] The excavation blades 14 are provided at intervals in the radial direction of the excavation shaft 11 and extend downward from the excavation wings 12, 13. In the following description, the radial direction means the radial direction of the excavation shaft 11 unless otherwise specified. In detail, the excavation blade 14 comprises a plurality of upper excavation blades 15 arranged at a radially outer position on the excavation wings 12, 13, and a plurality of lower excavation blades 16 arranged radially inward and below the upper excavation blades 15.

[0015] 2, when the excavation blade 12 is rotated by approximately 180° in the rotation direction R, the excavation blade 12 overlaps with the excavation blade 13. In FIG. In detail, the excavation wings 12, 13 integrally comprise an excavation wing main body 20 that extends radially outward from the outer periphery of the excavation shaft and supports the upper excavation blade 15, and an extension wing portion 21 that extends diagonally downward in the direction of rotation R from a portion of the excavation wing main body 20 that is radially inward from the upper excavation blade 15.

[0016] The excavator blade main body 20 has a plate shape extending in the radial direction perpendicular to the axis 11a in the side view of FIG. When the excavation blade main body 20 is viewed from the radially outer side, the excavation blade main body 20 has a plate shape that is inclined downward as it approaches the rotation direction R.

[0017] The upper excavation blade 15 is fixed to the lower surface of the excavation blade main body 20. The upper excavation blade 15 extends obliquely downward in the direction of rotation R along the lower surface of the excavation blade main body 20. 2 shows an imaginary straight line L1 that passes through the center of the drilling axis 11 and extends radially outward along the drilling blade body 20. A plurality of upper drilling blades 15 are linearly arranged on the straight line L1 at intervals in the radial direction.

[0018] The extension wing portion 21 is plate-shaped and extends obliquely downward in the direction of rotation R from the leading edge of the excavation wing main body portion 20 in the rotation direction R along the inclination of the excavation wing main body portion 20. The inner edge 21a of the extension wing portion 21 in the radial direction is connected to the outer periphery of the excavation shaft 11. The leading edge of the extension wing portion 21 in the rotation direction R is located at a position shifted by a predetermined angle θ from the straight line L1 in the rotation direction R. Figure 2 shows an imaginary straight line L2 that passes through the center of the drilling axis 11 and extends radially outward along the leading edge of the extension wing portion 21.

[0019] The lower excavation blade 16 is fixed to the extension wing portion 21 and is therefore located radially inward and below the upper excavation blade 15 . The lower excavation blade 16 is fixed to the lower surface of the extension wing portion 21. The lower excavation blade 16 extends obliquely downward in the direction of rotation R along the lower surface of the excavation wing main body portion 20. A plurality of lower excavation blades 16 are linearly arranged on the straight line L2 at intervals in the radial direction.

[0020] 2, when viewed in the axial direction of the excavation shaft 11, the arrangement of the lower excavation blades 16 is arranged at a different position in the rotational direction R from the arrangement of the upper excavation blades 15. In detail, the arrangement of the lower excavation blades 16 is arranged at a position advanced by a predetermined angle θ in the rotational direction R from the arrangement of the upper excavation blades 15.

[0021] 1 and 2, the lower ends of the excavation blades 14 are located lower in the radial direction as the excavation blades 14 are closer to the excavation axis 11. The lower ends are cutting edges of the excavation blades 14. A lower end position line B, which is a straight line drawn along adjacent lower ends, is inclined so that the line is located lower as it approaches the excavation axis 11.

[0022] Specifically, in the lower excavation blade 16, the lower end of the lower excavation blade 16a closest to the excavation axis 11 is positioned at the lowest position. The lower excavation blade 16 is positioned farther away from the excavation axis 11 in the radial direction, the higher the position of the lower end.

[0023] In addition, with respect to the upper excavation blade 15, the lower end of the upper excavation blade 15a closest to the excavation axis 11 is positioned at the lowest position. The further the upper excavation blade 15 is positioned radially away from the excavation axis 11, the higher the position of the lower end of the upper excavation blade 15 is.

[0024] When excavating the ground, the ground excavation device 10 is lowered to the excavation surface while rotating the excavation shaft 11 in the rotation direction R, and the lower excavation blade 16a, which is closest to the excavation shaft 11 and located at the bottom, hits the excavation surface first, starting excavation. Then, as excavation proceeds, the lower excavation blades 16 successively hit the excavation surface starting from the one closest to the excavation shaft 11 in the radial direction, thereby performing excavation. As the excavation becomes deeper, the upper excavation blade 15a that is closest to the excavation axis 11 comes into contact with the excavation surface, and excavation by the upper excavation blade 15 begins. Then, as excavation progresses, the upper excavation blades 15 come into contact with the excavation surface in sequence starting from the one closest to the excavation axis 11, thereby performing excavation. In this way, in the ground excavation device 10, the radially inner excavation blade 14 excavates first, and as excavation progresses, the radially outer parts are excavated sequentially. This allows the lower excavation blade 16 and the upper excavation blade 15 to come into contact with the excavation surface more strongly than, for example, when multiple excavation blades are brought into contact with the excavation surface simultaneously, thereby improving excavation capacity.

[0025] In addition, a lower excavation blade 16 is provided on an extension blade portion 21 that extends downward from the excavation blade main body portion 20 in the direction of rotation R, radially inward of the upper excavation blade 15, and the arrangement of the lower excavation blades 16 is positioned at a position that is a predetermined angle θ in the rotation direction R relative to the arrangement of the upper excavation blades 15. Therefore, the excavation powder generated by the lower excavation blade 16 is efficiently discharged along the extension wing portion 21 to the rear and above the lower excavation blade 16 in the rotation direction R. This allows the excavation powder to be efficiently discharged, reducing the excavation resistance caused by the excavation powder and improving the excavation capacity of the ground excavation device 10.

[0026] FIG. 3 is a diagram showing the trajectory of rotation of the excavation blade 14 caused by the rotation of the excavation shaft 11. As shown in FIG. 1 to 3, the upper excavation blade 15 includes one upper excavation blade 15X provided on the excavation wing 12 and the other upper excavation blade 15Y provided on the excavation wing 13. As shown in FIG. One upper excavation blade 15X and the other upper excavation blade 15Y are arranged so that the position where one upper excavation blade 15X is arranged and the position where the other upper excavation blade 15Y is arranged are different in the radial direction.

[0027] The lower excavation blade 16 includes a lower excavation blade 16X provided on the excavation wing 12 and a lower excavation blade 16Y provided on the excavation wing 13. One lower excavation blade 16X and the other lower excavation blade 16Y are arranged so that the position where one lower excavation blade 16X is arranged and the position where the other lower excavation blade 16Y is arranged are different in the radial direction.

[0028] In Figure 3, when the drilling shaft 11 rotates, the rotational trajectory of one upper drilling blade 15X is shown as trajectory X1, the rotational trajectory of the other upper drilling blade 15Y is shown as trajectory Y1, the rotational trajectory of one lower drilling blade 16X is shown as trajectory X2, and the rotational trajectory of the other lower drilling blade 16Y is shown as trajectory Y2.

[0029] When the drilling shaft 11 rotates, as shown in Figure 3, when viewed in the axial direction of the drilling shaft 11, a non-digging section 15N is formed between the rotation trajectory X1 of one upper drilling blade 15X, through which one upper drilling blade 15X does not pass, and the rotation trajectory Y1 of the other upper drilling blade 15Y passes through the non-digging section 15N. Therefore, the portion of the locus X1 is excavated by one upper excavation blade 15X, and the non-excavation portion 15N that is not excavated by one upper excavation blade 15X is excavated by the other upper excavation blade 15Y.

[0030] Furthermore, when the drilling shaft 11 rotates, a non-digging section 16N is formed between the rotation trajectory X2 of one lower drilling blade 16X, through which one lower drilling blade 16X does not pass, and the rotation trajectory Y2 of the other lower drilling blade 16Y passes through the non-digging section 16N. Therefore, the portion of the locus X2 is excavated by one lower excavation blade 16X, and the non-excavation portion 16N that is not excavated by one lower excavation blade 16X is excavated by the other lower excavation blade 16Y.

[0031] As described above, according to the first embodiment to which the present invention is applied, the ground excavation device 10 comprises the excavation shaft 11 that can rotate around an axis 11a extending in the vertical direction, a pair of excavation wings 12, 13 extending radially outward from the excavation shaft 11, and a plurality of excavation blades 14 that are provided at intervals in the radial direction and extend downward from the excavation wings 12, 13. The lower ends of the excavation blades 14 that are closer to the excavation shaft 11 in the radial direction are located lower. According to this configuration, when the ground excavation device 10 is lowered to excavate the ground, the excavation blade 14 closest to the excavation axis 11 hits the excavation surface first to start excavation, and as excavation progresses, the excavation blades 14 closest to the excavation axis 11 hit the excavation surface sequentially to complete excavation. This allows each excavation blade 14 to hit the excavation surface more strongly than when, for example, multiple excavation blades hit the excavation surface simultaneously, improving excavation capacity.

[0032] In addition, the drilling blade 14 comprises an upper drilling blade 15 and a lower drilling blade 16 arranged radially inward and below the upper drilling blade 15, and when viewed in the axial direction of the drilling shaft 11, the arrangement of the lower drilling blades 16 is arranged at a different position in the rotational direction R of the drilling shaft 11 than the arrangement of the upper drilling blades 15. According to this configuration, the arrangement of the lower excavation blades 16, which are provided radially inward and below the upper excavation blades 15, is positioned at a different position in the rotation direction R of the excavation shaft 11 from the arrangement of the upper excavation blades 15, so that the excavation powder generated by the lower excavation blades 16 is discharged behind the lower excavation blades 16 in the rotation direction of the excavation shaft 11 and above the lower excavation blades 16 moving downward. Therefore, the excavation powder can be discharged efficiently, the excavation resistance due to the excavation powder can be reduced, and the excavation capacity can be improved.

[0033] In addition, the excavation wings 12, 13 are provided with an excavation wing main body 20 that extends radially outward from the excavation axis 11 and supports the upper excavation blade 15, and an extension wing portion 21 that extends diagonally downward in the direction of rotation R from a portion of the excavation wing main body 20 that is radially inward from the upper excavation blade 15, and a lower excavation blade 16 is provided on the extension wing portion 21. With this configuration, the excavation powder generated by the lower excavation blade 16 can be efficiently discharged rearward and upward of the lower excavation blade 16 in the rotation direction R along the extension wing portion 21. This reduces the excavation resistance caused by the excavation powder, improving the excavation capacity. Furthermore, because the lower excavation blade 16 is provided on the extension wing portion 21 extended from the excavation blade main body portion 20, the lower excavation blade can be supported with a simple structure, and the rigidity of the excavation blade main body portion 20 can be used to firmly support the lower excavation blade 16, improving the excavation capacity of the lower excavation blade 16.

[0034] Furthermore, the excavation blade 14 includes one upper excavation blade 15X and one lower excavation blade 16X provided on one excavation wing 12, and the other upper excavation blade 15Y and the other lower excavation blade 16Y provided on the other excavation wing 13. When the excavation shaft 11 rotates, non-digging sections 15N, 16N through which the one upper excavation blade 15X and the one lower excavation blade 16X do not pass are formed between the rotation trajectories X1, X2 of the one upper excavation blade 15X and the one lower excavation blade 16X when viewed in the axial direction of the excavation shaft 11. The rotation trajectories Y1, Y2 of the other upper excavation blade 15Y and the other lower excavation blade 16Y when the excavation shaft 11 rotates pass through the non-digging sections 15N, 16N. According to this configuration, non-digging sections 15N, 16N are formed between the rotation trajectories X1, X2 of the one upper excavation blade 15X and the one lower excavation blade 16X, through which the one upper excavation blade 15X and the one lower excavation blade 16X do not pass. This reduces the excavation resistance of the one upper excavation blade 15X and the one lower excavation blade 16X, allowing efficient excavation by the one upper excavation blade 15X and the one lower excavation blade 16X. The rotation trajectories Y1, Y2 of the other upper excavation blade 15Y and the other lower excavation blade 16Y pass through the non-digging sections 15N, 16N, allowing the other upper excavation blade 15Y and the other lower excavation blade 16Y to excavate areas not excavated by the one upper excavation blade 15X and the one lower excavation blade 16X. This reduces excavation resistance and allows the excavation blade 14 to apply excavation to a wide area, improving excavation capacity.

[0035] [Second embodiment] A second embodiment to which the present invention is applied will be described below with reference to Figures 4 to 6B. In this second embodiment, parts configured in the same manner as in the first embodiment are given the same reference numerals and descriptions thereof will be omitted. The second embodiment differs from the first embodiment in that the excavation blade 214 is detachable and the angle thereof is changeable.

[0036] FIG. 4 is a side view of a ground excavation device 210 according to the second embodiment of the present invention. The ground drilling device 210 comprises a drilling shaft 11, drilling wings 12 and 13, and a drilling blade 214 provided on the drilling wings 12 and 13. The drilling blade 214 is arranged in the same manner as the drilling blade 14 (FIG. 1), except that it is detachable from the drilling wings 12 and 13 and its angle is changeable. In the second embodiment, the upper drilling blade 15 (FIG. 1) is illustrated as the upper drilling blade 215, and the lower drilling blade 16 (FIG. 1) is illustrated as the lower drilling blade 216.

[0037] Fig. 5A is a diagram showing an attached state of the digging blade 214. Fig. 5B is a diagram showing a state in which the angle of the digging blade 214 has been changed. The digging blade 214 is attached to the digging wing 12 and the digging wing 13 in the same manner, but here, the digging blade 214 attached to the digging wing 13 will be described as an example. The excavation blade 214 is attached to the underside of the excavation wing 13. Figures 5A and 5B are views of the excavation blade 214 viewed from a direction directly facing the underside of the excavation wing 13. The excavation blade 214 in Figures 5A and 5B is a pointed bit suitable for excavating ground that contains a lot of sand.

[0038] The digging blade 214 is attached to the underside of the digging wing 13 by a fastener 230 that passes through the top of the digging blade 214 and a shaft 231 that passes through the lower part of the fastener 230 on the digging blade 214 . The shaft 231 is located midway between the upper end of the digging blade 214 and the lower end of the digging blade 214 . The fastener 230 and the shaft 231 are located at the center of the digging blade 214 in the width direction.

[0039] The shaft 231 is inserted into a through hole (not shown) provided in the excavation blade 214 and fixed to a shaft fixing hole 13a provided on the underside of the excavation blade 13. In this embodiment, the shaft 231 is a bolt that is inserted into the through hole and screwed into the shaft fixing hole 13a. When the fastener 230 is removed, the excavation blade 214 is rotatable in a rotation direction T around the shaft 231 as the center of rotation.

[0040] The digging blade 214 has a hole 214a at its upper portion through which a fastener 230 is inserted. Further, the bottom surface of the excavation wing 13 is provided with fixing holes 13b and 13c into which the fastener 230 inserted through the hole 214a is screwed. The fixing holes 13b and 13c are provided at different positions in the rotation direction T.

[0041] Specifically, a plurality of fixing holes 13b and 13c are provided at different positions on the movement locus of hole 214a when excavation blade 214 rotates in rotation direction T around shaft 231 as the rotation center. In FIG. 5A, fixing hole 13b is located directly above shaft 231, and fixing hole 13c is located at a position shifted by a predetermined angle in the rotation direction T with respect to fixing hole 13b. In this embodiment, the shaft 231 is a bolt that is screwed into the fixing holes 13b and 13c. The digging blade 214 is also fastened to the digging wing 13 by the shaft 231. 4, shaft 231 extends in rotation direction R (FIG. 2) and is tilted in the up-down direction. That is, the extension direction (axial direction) of shaft 231 includes a component of rotation direction R.

[0042] Here, an example of a procedure for replacing the digging blade 214 and changing the angle will be described. When replacing the excavation blade 214, the excavation blade 214 can be removed from the excavation wing 13 by releasing the fastening by the fastener 230 and the shaft 231. Then, a replacement excavation blade 214 can be attached to the excavation wing 13 by the fastener 230 and the shaft 231. This makes it possible to easily replace the excavation blade 214. For example, when the excavation blade 214 needs to be replaced due to wear or the like, the excavation blade 214 can be easily replaced by attaching and detaching the fastener 230 and the shaft 231 at the excavation construction site without returning to a factory or the like.

[0043] 5A , the worker releases the fastener 230 that is threaded into the fixing hole 13b and loosens the shaft 231. Next, as shown in FIG. 5B , the worker rotates the excavation blade 214 in the rotation direction T around the shaft 231, and then fastens the fastener 230 into the fixing hole 13c and re-fastens the shaft 231. As a result, the angle of the excavation blade 214 is changed in the radial direction of the excavation shaft 11, and the position of the lower end 214b of the excavation blade 214 is changed in the radial direction of the excavation shaft 11.

[0044] 6A and 6B are diagrams showing digging blades 214 having other shapes. The digging blade 214 may be a clay bit suitable for digging ground containing a hard clay layer, as shown in FIG. 6A. 6B, the excavation blade 214 may be a conical bit that is suitable for excavating hard ground such as bedrock. The shape of the excavation blade 214 is not particularly limited.

[0045] As described above, according to the second embodiment to which the present invention is applied, the excavation blade 214 is detachably attached to the excavation wing 13 by the fastener 230 and is replaceable. According to this configuration, the drilling blade 214 can be easily attached and detached to the drilling wing 13 and replaced by fastening and unclamping the fastener 230, making it easy to replace a damaged or worn drilling blade 214 and change the type of drilling blade 214, allowing for flexible response depending on the wear condition of the drilling blade 214 and the condition of the ground, etc.

[0046] In addition, the excavation blade 214 is rotatable around an axis 231 that is provided on the excavation wing 13 and inserted into the excavation blade 214, and can be fixed by a fastener 230 while changing the rotation angle around the axis 231. According to this configuration, the angle of the excavation blade 214 can be changed by rotating the excavation blade 214 around the axis 231 provided on the excavation blade 13, so that the angle of the excavation blade 214 can be changed to an angle suitable for the ground conditions, thereby improving excavation capacity.

[0047] In addition, the fastener 230 is inserted into a hole 214a provided in the drilling blade 214, and the drilling wing 13 has fixing holes 13b and 13c into which the fastener 230 can be fastened, and the fixing holes 13b and 13c are provided at multiple positions different from each other in the rotational direction T around the axis 231. According to this configuration, the drilling blade 214, which is fastened to the fixing hole 13b by inserting the fastener 230 into the hole 214a, can be fixed to another fixing hole 13c located at a different position in the rotation direction T centered on the axis 231, thereby making it easy to change and fix the angle of the drilling blade 214.

[0048] [Variations] Fig. 7A is a diagram showing a modified example of the second embodiment, and Fig. 7B is a diagram showing a state in which the angle of the digging blade 214 is changed from the state in Fig. 7A. 7A and 7B are views of the excavation blade 13 to which the excavation blade 214 is attached, as viewed from the radially outer side of the excavation shaft 11, as indicated by arrow V in FIG.

[0049] In this variant, the digging wing 13 comprises a digging wing fixing surface 350 on a radial surface of the digging wing 13 to which the digging blade 214 is attached. The digging blade 214 is secured to the digging blade fixing surface 350 by a fastener 330 and a shaft 331 . Here, fastener 330 is the same part as fastener 230 (FIG. 5A), and shaft 331 is the same part as shaft 231 (FIG. 5A), but for distinction, different reference numerals are used in the following description.

[0050] The drilling blade fixing surface 350 is provided with a shaft fixing hole 313a to which the shaft 331 is fastened, and fixing holes 313b and 313c to which the fastener 330 is fastened.

[0051] The shaft 331 is inserted into a through hole (not shown) provided in the excavation blade 214 and fixed to the shaft fixing hole 313a. In this embodiment, the shaft 331 is a bolt that is inserted into the through hole and screwed into the shaft fixing hole 313a, and extends in the radial direction of the excavation shaft 11. When the fastener 330 is removed, the excavation blade 214 is rotatable in a rotation direction T2 around the shaft 331 as the center of rotation.

[0052] Above the shaft fixing hole 313a on the drilling blade fixing surface 350, fixing holes 313b and 313c are provided into which the fastener 330 inserted through the hole 214a is screwed. A plurality of fixing holes 313b and 313c are provided at different positions in the rotation direction T2.

[0053] Specifically, a plurality of fixing holes 313b and 313c are provided at different positions on the movement trajectory of hole 214a when excavation blade 214 rotates in rotation direction T2 around shaft 331 as the center of rotation. In FIG. 7A, fixing hole 313b is located directly above shaft 331, and fixing hole 313c is located at a position shifted by a predetermined angle in rotation direction T2 relative to fixing hole 313b. In this modification, the shaft 331 is a bolt that is screwed into the fixing holes 313b, 313c, and extends in the radial direction of the excavation shaft 11. The excavation blade 214 is fastened to the excavation blade fixing surface 350 by the shaft 331 as well.

[0054] Here, an example of a procedure for replacing and changing the angle of the digging blade 214 in FIG. 7A will be described. When replacing the digging blade 214, the digging blade 214 can be removed from the digging wing 13 by releasing the fastening by the fastener 330 and the shaft 331. Then, a replacement digging blade 214 can be attached to the digging wing 13 by the fastener 330 and the shaft 331.

[0055] 7A , the worker releases the fastener 330 that is threaded into the fixing hole 313b and loosens the shaft 331. Next, as shown in FIG. 7B , the worker rotates the excavation blade 214 in the rotation direction T2 around the shaft 331, and then fastens the fastener 330 to the fixing hole 313c and fastens the shaft 331 again. As a result, the angle of the excavation blade 214 is changed in the rotation direction T2, and the position of the lower end 214b of the excavation blade 214 is changed in the rotation direction R.

[0056] As described above, according to the modified example, the rotation angle of the excavation blade 214 can be changed around the axis 331 extending in the radial direction of the excavation shaft 11. According to this configuration, the angle of the digging blade 214 relative to the rotation direction R of the digging blade 214 during digging can be changed, and the rake angle and clearance angle of the digging blade 214 relative to the digging surface can be changed. Therefore, the angle of the digging blade 214 can be changed to an angle suitable for the ground condition, and digging capacity can be improved.

[0057] Although one embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment, and unless otherwise limited in the above description, various modifications and variations are possible within the spirit and scope of the present invention as defined in the claims. For example, the configurations of the above-described embodiment may be added or deleted as appropriate, and the configurations of one embodiment may be incorporated into other embodiments. Furthermore, the effects of the above-described embodiment are merely examples of the effects resulting from the present invention, and do not mean that the effects of the present invention are limited to the above-described effects. In the above embodiment, the fasteners 230, 330 and the shafts 231, 331 are described as bolts, but the present invention is not limited to this. For example, at least one of the fasteners 230, 330 and the shafts 231, 331 may be configured as a pin disposed on the excavation blade, and may be fixed by inserting the pin. In addition, in the above embodiment, the rotation trajectories Y1, Y2 of the other upper excavation blade 15Y and the other lower excavation blade 16Y when the excavation shaft 11 rotates pass through the non-excavation sections 15N, 16N, but it is sufficient for the trajectories Y1, Y2 to pass through at least a portion of the non-excavation sections 15N, 16N. Furthermore, the fixing holes 213b and 213c and the fixing holes 13b and 313c are provided in two locations, respectively, but the fixing holes may be provided in three or more locations. Furthermore, in the above embodiments, the ground excavation equipment 10, 210 is used as a single shaft, but the ground excavation equipment 10, 210 can also be used in a multi-shaft construction method in which a plurality of ground excavation equipment 10, 210 are lined up to perform excavation. Taking the ground excavation equipment 10 as an example, in a bi-shaft construction method using two ground excavation equipment 10, one ground excavation equipment 10 and the other ground excavation equipment 10 are arranged in parallel, and one ground excavation equipment 10 and the other ground excavation equipment 10 are rotated independently of each other, and one ground excavation equipment 10 is rotated in the opposite direction to the other ground excavation equipment 10. In the biaxial construction method, one ground drilling device 10 and the other ground drilling device 10 are positioned vertically offset so that the excavation wings 12 of one ground drilling device 10 and the excavation wings 12 of the other ground drilling device 10 are in different positions in the vertical direction, and one ground drilling device 10 and the other ground drilling device 10 are positioned so that the excavation range of the excavation wings 12 of one ground drilling device 10 overlaps with the excavation range of the excavation wings 12 of the other ground drilling device 10 when viewed in the axial direction. In another example of the two-axis construction method, the axis distance is set so that the outer periphery of the excavation range of the excavation wing 12 of one ground excavation device 10 and the outer periphery of the excavation range of the excavation wing 12 of the other ground excavation device 10 are in a tangent circle state. Here, the axis distance is the distance between the excavation axis 11 of one ground excavation device 10 and the excavation axis 11 of the other ground excavation device 10. In this tangent circle state, patterns 1 and 2 for the arrangement of the ground excavation device 10 will be explained below. In pattern 1, one ground drilling device 10 and the other ground drilling device 10 are positioned vertically offset so that the drilling wings 12 of one ground drilling device 10 and the drilling wings 12 of the other ground drilling device 10 are at different positions in the vertical direction. In pattern 2, one ground drilling device 10 and the other ground drilling device 10 are positioned at the same position in the vertical direction, and the ground drilling devices 10 are driven so that the phase of rotation of the drilling blade 12 of one ground drilling device 10 is different from the phase of rotation of the drilling blade 12 of the other ground drilling device 10 (for example, 90° different). By arranging in pattern 1 or pattern 2, interference between adjacent excavation blades 12 can be avoided, and good excavation can be achieved with the two-axis system. In yet another example of the biaxial construction method, the axis distance may be set so that the excavation range of the excavation wing 12 of one ground excavator 10 does not overlap with the excavation range of the excavation wing 12 of the other ground excavator 10. In this case of an independent arrangement in which the excavation ranges of one ground excavator 10 and the other ground excavator 10 do not overlap and are independent of each other, the excavation wing 12 of one ground excavator 10 does not interfere with the excavation wing 12 of the other ground excavator 10, even without the arrangement of Pattern 1 or Pattern 2. Therefore, excavation can be performed even if the one ground excavator 10 and the other ground excavator 10 are arranged at the same vertical position. However, by arranging the excavators in Pattern 1 or Pattern 2 in this independent arrangement state, interference between adjacent excavation wings 12 can be prevented even when the arrangement is changed from the independent arrangement state to the tangent circle arrangement. This allows for an easy transition from the independent arrangement state to the tangent circle arrangement. Furthermore, the multi-axis construction method is not limited to the arrangement of two ground excavation devices 10, but excavation may be carried out by arranging three or more ground excavation devices 10 in parallel. [Explanation of symbols]

[0058] 10,210: Earth drilling equipment 11: Drilling axis 11a: Axis 12: Excavation wing (one of the excavation wings) 13: Excavation wing (the other excavation wing) 13a, 313a: Axis fixing hole 13b, 13c: Fixed hole 14,214:Drilling blade 15,215: Upper digging blade 15a: Upper digging blade (the upper digging blade closest to the digging axis) 15X: One upper digging blade (one digging blade) 15Y: The other upper digging blade (the other digging blade) 15N, 16N: Non-excavation area 16,216: Lower digging blade 16a: Lower digging blade (the lower digging blade closest to the digging axis) 16X: One lower digging blade (one digging blade) 16Y: The other lower digging blade (the other digging blade) 20: Excavation wing main body 21: Extension wing part 214a: Hole 214b: Lower end (lower end of digging blade) 230, 330: Fasteners 231,331:Axis 350: Drilling wing fixed surface B: Bottom position line L1: Straight line (a virtual straight line passing through the center of the drilling axis and extending radially outward along the drilling wing body) L2: Straight line (a virtual straight line passing through the center of the drilling axis and extending radially outward along the leading edge of the extension wing) R: Rotation direction (rotation direction of drilling shaft) T, T2: Direction of rotation (direction of rotation around the axis) X1, X2: Trajectory (trajectory of rotation of one of the excavation blades) Y1, Y2: Trajectory (trajectory of rotation of the other excavation blade)

Claims

1. A ground excavation device comprising: a drilling shaft rotatable around an axis extending in the vertical direction; a pair of drilling wings extending radially outward from the drilling shaft; and a plurality of drilling blades spaced apart in the radial direction and extending downward from the drilling wings. A ground excavation device in which the lower end of the excavation blade is located lower in the radial direction as the excavation blade is closer to the excavation axis.

2. The excavation blade includes an upper excavation blade and a lower excavation blade provided radially inward and below the upper excavation blade, The ground excavation device according to claim 1 , wherein, when viewed in the axial direction of the excavation shaft, the arrangement of the lower excavation blades is arranged at a different position in the rotation direction of the excavation shaft from the arrangement of the upper excavation blades.

3. The excavation wing includes an excavation wing main body portion that extends radially outward from the excavation shaft and supports the upper excavation blade, and an extension wing portion that extends obliquely downward in the rotation direction of the excavation shaft from a portion of the excavation wing main body portion that is radially inner than the upper excavation blade, The earth excavation device according to claim 2, wherein the lower excavation blade is provided on the extension wing portion.

4. The earth excavation device according to claim 1 , wherein the excavation blade is detachably attached to the excavation wing by a fastener and is replaceable.

5. A ground excavation device as described in claim 4, wherein the excavation blade is rotatable around an axis provided on the excavation wing and inserted into the excavation blade, and can be fixed by the fastener in a state where the rotation angle around the axis is changed.

6. The fastener is inserted into a hole provided in the digging blade, The ground excavation device according to claim 5 , wherein the excavation blade has a fixing hole into which the fastener can be fastened, and the fixing hole is provided at a plurality of different positions in the rotation direction around the axis.

7. The ground excavation device according to claim 5 or 6, wherein the excavation blade is capable of changing a rotation angle about the axis extending in a radial direction of the excavation shaft.

8. The excavation blade includes one excavation blade provided on one of the excavation wings and the other excavation blade provided on the other excavation wing, A ground excavation device as described in claim 1, wherein when the drilling shaft rotates, a non-digging section is formed between the rotation trajectory of one of the drilling blades when viewed in the axial direction of the drilling shaft, through which one of the drilling blades does not pass, and the rotation trajectory of the other drilling blade when the drilling shaft rotates passes through at least a part of the non-digging section.

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